The present invention relates to a shaving system of the wet shave type, more particularly to a shaving system with an improved shaving aid composite.
It is now well known that shaving comfort can be enhanced by affixing to a razor cartridge a shaving aid composite, also known as a lubricating strip, which continuously releases a shaving aid, typically a lubricant, during the shaving process. See, for example, U.S. Pat. No. 4,170,821 and GB 2,024,082. The shaving aid composite generally comprises a water-insoluble polymer matrix, typically polystyrene, and a water-soluble shaving aid, typically polyethylene oxide, which leaches out of the composite during shaving to enhance shave comfort.
Unfortunately, conventional shaving aid composites suffer from the disadvantage that they release an insufficient amount of the shaving aid, particularly after the first three or four shaves where release of the shaving aid may drop off to negligible quantities. Accordingly, recent efforts have been made to improve shaving aid composites so as to enhance and prolong release of the shaving aid. Such efforts have resulted in improved shaving aid composites which include the following: incorporation of low molecular weight release enhancing agent, such as polyethylene glycol, into the matrix, disclosed in U.S. Pat. No. 5,113,585; the use of ethylene vinyl acetate copolymer as the matrix material, disclosed in U.S. Pat. No. 5,349,750; incorporation of a water-swellable polymer such as Salsorb 84, a cross-linked polyacrylic, disclosed in (U.S. Ser. No. 08/121,153); incorporation of a compatibilizer material such as polyethylene oxide-polypropylene oxide copolymer (e.g. Poloxamer 182), disclosed in U.S. Pat. No. 5,454,164; filed Mar. 17, 1994 and co-extrusion of a core comprising a water-leachable shaving aid within a sheath of water-insoluble polymer, wherein the sheath has a plurality of openings to facilitate release of the shaving aid, disclosed in (U.S. Ser. No. 08/332,293 now abandoned). All of the aforementioned patents or patent applications are incorporated herein by reference.
It has also been suggested in U.S. Pat. No. 5,095,619 that a water-insoluble essential oil, such as menthol, may be advantageously included in a shaving aid composite. However, it has been found in practice that a substantial amount of the essential oil is lost due to volatilization prior to use, rendering the composite unable to deliver an effective amount of the essential oil. It is an object of the present invention to provide a shaving aid composite (i.e. lubricating strip) which is capable of retaining during normal storage conditions substantially all of a skin-soothing agent, such as an essential oil or cooling agent, included during fabrication of the composite and delivering an effective amount of the skin-soothing agent during use.